Investigating the physical processes that impact reservoir delta fish passage and evaluating potential solutions

Project ID: 22065
Principal Investigator: Colin Byrne
Research Topic: Fish Passage and Entrainment
Funded Fiscal Years: 2022, 2023 and 2024
Keywords: None

Research Question

How do reservoir deltas affect fish passage compared to natural lakes and streams, and how can fish passage be improved by considering modifications to delta channel width and depth, promoting woody vegetation along stream banks, preventing downstream growth of delta surfaces, and managing the seasonal and annual fluctuations in reservoir pool water surface?

We hypothesize that unique geomorphic processes in reservoir delta environments cause fish passage issues that are more severe than natural lakes and streams. Fluctuating water surface levels in reservoirs are often not timed with fish life cycle histories and natural flow hydrographs. Further, the reservoir water surface influences delta sedimentation and woody vegetation growth, which may cause wider and shallower channels. Fish need a channel with sufficient flow depth, longitudinal slope, substrate, and cover to migrate from reservoirs to upstream reaches.

We also hypothesize that fish passage in reservoir delta environments can be improved by considering a range of solutions from physical modifications of delta channels, control of delta sedimentation and growth, and management of reservoir pool water surface elevations over time.

This research proposes a two-step approach that first investigates the root cause (i.e., the physical processes) of fish passage limitations in reservoir delta channels. Secondly, a better understanding of the physical processes will be used to develop and evaluate solutions with the goal of improving fish passage through reservoir deltas.

Need and Benefit

This interdisciplinary research will inform Reclamation's knowledge of how geomorphic processes at reservoir tributary deltas directly impact fish passage and habitat. Solutions to promote fish passage will be evaluated through data analysis and numerical modeling and will also inform aspects of water operations, sediment management, and climate change and variability. The research has been proposed with input from the EN research coordinator, who has reviewed the proposal prior to submission.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Contact the Principal Investigator for information about these documents.

Return to Research Projects

Last Updated: 6/22/20